Poster abstracts

Poster number 15 submitted by Timothy Faw

Eccentric-focused downhill walking training increases myelin in the brains of individuals with spinal cord injury

Timothy D. Faw (Neuroscience Graduate Program), Lise Worthen-Chaudhari (Department of Physical Medicine and Rehabilitation, The Ohio State University), James P. Schmiedeler (Department of Aerospace and Mechanical Engineering, Notre Dame University), Dana M. McTigue (Department of Neuroscience, The Ohio State University), Lara A. Boyd (Department of Physical Therapy, University of British Columbia), D. Michele Basso (School of Health and Rehabilitation Sciences)

Abstract:
Activity-dependent myelin plasticity has emerged as a novel mechanism of neuroplasticity with the potential to support functional recovery after central nervous system (CNS) trauma. In fact, animal studies indicate that new myelin formation is required for motor skill learning in the intact CNS. While traditional activity-based rehabilitation paradigms produce modest functional gains after spinal cord injury (SCI), deficits in eccentric motor control persist, making independent ambulation impossible for most individuals. Eccentric-focused, downhill (DH) treadmill training is a novel, challenging intervention that promotes greater skill learning of locomotion in rodent SCI. Therefore, the purpose of this study was to determine the extent of functional recovery and myelin plasticity induced by a 12-week DH training program in individuals with chronic, motor incomplete SCI (n=3). DH training consisted of four, 5-min bouts of walking on a 10% decline treadmill separated by 5-min seated rest breaks, delivered 3 days/week. We assessed gait speed, walking endurance, balance, and neuromuscular recovery prior to (Pre), immediately following (Post), and 4 weeks after the 12-week training intervention (Follow-up). Multicomponent T2 relaxation imaging of the brain occurred at Pre and Post time points only. Two out of three individuals increased gait speed beyond the minimal detectable change by the follow-up time point and one surpassed the minimal clinically important difference. Interestingly, changes in gait speed continued after training had ended, suggestive of motor learning. Significant increases in myelin water fraction, a histopathologically validated marker of CNS myelination, occurred in brain regions associated with motor learning (p<.05) and across all brain regions (p<.05) after training. These data suggest that eccentric-focused DH training targeting persistent locomotor deficits promotes locomotor learning and myelin plasticity in humans with SCI.

References:
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- McKenzie IA, Ohayon D, Li H, et al. Motor skill learning requires active central myelination. Science. 2014;346(6207):318-322. doi:10.1126/science.1254960.
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Keywords: Myelin Plasticity, Motor Learning, Spinal Cord Injury